The S-100B substudy of the GLUTAMICS trial: Glutamate infusion not associated with sustained elevation of plasma S-100B after coronary surgery

SummaryBackground & aimsConcerns have been raised about potential neurological injury related to exogenous glutamate. In cardiac surgery glutamate has been administered as a putative cardioprotective agent by cardioplegia or intravenous infusion. In the GLUTAMICS trial, in addition to surveillance of clinical neurological injuries, a prespecified subgroup was analyzed with regard to postoperative S-100B levels to detect potential subclinical neurological injury related to glutamate infusion.MethodsSixty-nine patients operated on for unstable coronary syndrome were randomized to intravenous infusion of glutamate (n = 35) or saline (n = 34) perioperatively. Plasma levels of S-100B were obtained on the third postoperative day.ResultsS-100B in the glutamate group and the control group were 0.079 ± 0.034 μg/L and 0.090 ± 0.042 μg/L respectively (p = 0.245). There were no patients with stroke or mortality. Three patients in the control group and two in the glutamate group had postoperative confusion. These patients had significantly elevated S-100B compared with those without confusion (0.132 ± 0.047vs 0.081 ± 0.036 μg/L; p = 0.003). Overall, 21 patients had S-100B above reference level (≥0.10 μg/L) and these patients had significantly more calcifications in the ascending aorta on epiaortic scanning.ConclusionsIntravenous glutamate infusion during surgery for unstable coronary artery disease did not initiate a sustained elevation of plasma S-100B. Thus, no evidence for subclinical neurological injury related to glutamate infusion was found. In contrast, postoperative elevation of plasma S-100B was linked to calcification of the ascending aorta and postoperative confusion.